The currently the well established human review process for Papanicolaou smear analysis follows standards recommended by the Bethesda System. A trained cytotechnologist systematically views a slide at low magnification to identify areas of interest. When an area of interest is identified, the cytotechnologist views the area at high magnification where it is possible to distinguish abnormal cells according to changes in their structure and context.
In much the same way as a human reviews Papanicolaou smears, it is one motivation of the invention to scan slides at low magnification to detect possible areas of interest, then at high magnification, to scan those areas to locate possible abnormal cells or other cells of interest. As a cytotechnologist compares size, shape and density of cells against established criteria, it is an additional motive of the invention to compare objects according to criteria established during a training process.